In various machines and systems, for instance presses, torque is calculated according to the resultant press working torque.
This torque is sometimes too important when starting the machine and hence the instantaneous application thereof causes jolting and undesired effects in its kinematic chain.
This is why connection at a lower torque is required for a short space of time, after which, once the mechanism has been coupled and before the working phase is reached, it must be in a position to yield its full rated torque.
To achieve this, oil input pressure is controlled at below rating values during connection, thereafter to reach rated pressure. This requires sophisticated systems of electrovalves and pressure regulators fitted in the oil connection circuit, which is an expensive and complex solution that requires extensive servicing.
Furthermore the braking torque must be varied or regulated, and in this sense in the conventional conception of brake clutches, external hydraulic systems are also used operating therefrom, causing oil output from the piston not to be free, but at a controlled pressure, partly offsetting the force of the springs. This system is also expensive, and the brake clutch is usually taken apart and some of its springs are removed, which is in practice cumbersome, and not least fitting again the springs removed, if the initial position is to be resumed.